The present invention relates to a circuit configuration for a brake system having an anti-locking control for controlling the pressure build-up upon commencement of the control by generating pulse-type control signals capable to control multi-way valves that are inserted into pressure-fluid conduits leading to the wheel brakes, with the pressure, by dimensioning the pulse and pulse break times, being applicable first at a steep and then at a flatter gradient, and with the pressure build-up, in the first cycle after commencement of the control, being dependent on the preceding pressure drop and, in the other cycles, on the pressure increase in the preceding cycles.
A circuit configuration of the afore-described type has already been taught by DE-Patent 24 60 904 according to which the brake pressure, basically, during anti-locking control, first, is reincreased at a steep and, subsequently, at a flatter gradient. The steep pressure increase, preferably, is attained by an extended pulse while the flatter increase is attained by a short pulse which two pulses succeed one another at a relatively large interval, with the duration of the steep-gradient pressure rise being varied in response to the pressure build-up in the preceding control cycle(s). For dimensioning the steep phase of the first control cycle in respect of which there is no precedingly controlled pressure build-up, the level and duration, respectively, of the preceding brake pressure decrease will be taken into account.
According to European Patent Application No. 177 817, equally concerned with the pressure reincrease first at a steep and subsequently at a flatter gradient, it is known to render dependent the pressure level of the first pressure build-up pulse determining the phase of the steep pressure rise, in addition, on a quotient resulting from the maximum wheel acceleration divided by the sum of the amounts of maximum wheel acceleration and maximum wheel deceleration. In one example, the pressure level of the first pressure build-up pulse corresponds to the preceding pressure decrease multiplied by the above-mentioned quotient and a factor approximately "1".